Watch: violent clashes between supporters and protesters at Donald Trump rally in ChicagoPlay!01:26

I was on BBC Question Time this week and, as always, we ran through a test question before filming began: “Will Trump be president?” One audience member asked if he wasn’t reminiscent of Hitler. I replied that while his rhetoric is extreme and his policies wrong-headed, some of his positions are surprisingly moderate and it is hard to identify proof of personal prejudice. Moreover, many people are supporting him precisely because they are tired of being called “fascist” simply because they support controls on immigration. He’s riding a backlash against political correctness – and the violence in Chicago is only likely to increase sympathy for him. In the Trump imagination, Middle America is besieged by radical, anti-American voices trying to drown out alternative opinion. Shutting down a Trump rally won’t silence Trumpism. On the contrary, it affirms it. Why does the Left continue to make this mistake?

Trump's views are unconstitutional, illiberal and sometimes they trigger hate. But he did not take America to war in Iraq on flimsy evidence, establish Guantanamo in contravention of human rights law or licence the torture of enemy combatants.

Trump’s political style bears comparison not with Mussolini but George C Wallace, who ran for the presidency in 1968 and 1972 on a conservative populist ticket. Protestors turned up to his rallies, too – and he loved it. Wallace perfected the anti-hippie zinger. When kids shouted “F**k Wallace!” he replied: “Why don’t you try learnin’ some other four letter words – like W.A.S.H. and W.O.R.K.?” The confrontations added to the Alabamian's appeal, confirming him as "the only guy willing to take on the mob".

Wallace ran as a Democrat from the Deep South – a reminder that the history of demagoguery and racist innuendo runs at least as deep in the Democrats as it does the Republicans. Indeed, Wallace was routinely condemned by philosophical conservatives because they regarded him as a liberal with racist sensibilities. Exactly the same dynamic exists between Trump and the intellectual high-priests of modern Republicanism. To the scholars and the pundits of American conservatism, Trump is an interloper in the GOP and a threat to the Constitution. The Right is as alarmed by his authoritarian streak as the Left.

I would like to say that they should all have greater faith in their Constitution's ability to withstand populism. After all, if Trump won the presidency – which is highly unlikely – he would be bound by Congress, a military obliged to ignore illegal orders, the judiciary and the God-given rights enjoyed by every citizen. But the problem with any narrative that sees Trump as a fascist seeking to subvert America from within is that all of these fine institutions have already been subverted. Usually by the White House.

Trump is not a political crisis in isolation but, rather, a symptom of wider institutional failure. A symptom of American political decline.

Trump is a blowhard. His views are unconstitutional, illiberal and sometimes they trigger hate. But he did not take America to war in Iraq on flimsy evidence, establish Guantanamo in contravention of human rights law, licence the torture of enemy combatants, oversee the gargantuan NSA data-gathering operation, launch a dirty war of drone strikes against both terrorists and those unfortunate enough to live near them, undermine the religious freedoms of employers who do not want to subsidise the sex lives of their workers, overrule the states’ wishes on marriage, compel citizens to buy healthcare products or deport thousands of illegals through aggressive round-ups. No: these things were done by “moderate” Republicans and “liberal” Democrats.

Trump is not new. The violence in Chicago has been a part of American politics for a very long time. The angry nihilism of the far-Right has incubated for decades; the “no platform” tendency of the Left is authoritarianism by any other name. And the slow corruption of American republicanism – the growth of the state and the willingness of politicians to do anything to get votes – began long before The Donald threw his hair into the ring. Trump is not a political crisis in isolation but, rather, a symptom of wider institutional failure. A symptom of American political decline.